[PATCH 5.4.y] i40e: add mask to apply valid bits for itr_idx

[Sasha Levin <sashal@kernel.org>]

From: Lukasz Czapnik <lukasz.czapnik@intel.com>

[ Upstream commit eac04428abe9f9cb203ffae4600791ea1d24eb18 ]

The ITR index (itr_idx) is only 2 bits wide. When constructing the
register value for QINT_RQCTL, all fields are ORed together. Without
masking, higher bits from itr_idx may overwrite adjacent fields in the
register.

Apply I40E_QINT_RQCTL_ITR_INDX_MASK to ensure only the intended bits are
set.

Fixes: 5c3c48ac6bf5 ("i40e: implement virtual device interface")
Cc: stable@vger.kernel.org
Signed-off-by: Lukasz Czapnik <lukasz.czapnik@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
[ Added missing linux/bitfield.h header for FIELD_PREP macro ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index d8ba409122032..45ff778be65f1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2013 - 2018 Intel Corporation. */
 
+#include <linux/bitfield.h>
 #include "i40e.h"
 
 /*********************notification routines***********************/
@@ -393,7 +394,7 @@ static void i40e_config_irq_link_list(struct i40e_vf *vf, u16 vsi_id,
 		    (qtype << I40E_QINT_RQCTL_NEXTQ_TYPE_SHIFT) |
 		    (pf_queue_id << I40E_QINT_RQCTL_NEXTQ_INDX_SHIFT) |
 		    BIT(I40E_QINT_RQCTL_CAUSE_ENA_SHIFT) |
-		    (itr_idx << I40E_QINT_RQCTL_ITR_INDX_SHIFT);
+		    FIELD_PREP(I40E_QINT_RQCTL_ITR_INDX_MASK, itr_idx);
 		wr32(hw, reg_idx, reg);
 	}
 
-- 
2.51.0